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High thermoelectric performance in (Bi_(0.25)Sb_(0.75)_2 Te_3 due to band convergence and improved by carrier concentration control

Kim, Hyun-Sik and Heinz, Nicholas A. and Gibbs, Zachary M. and Tang, Yinglu and Kang, Stephen D. and Snyder, G. Jeffrey (2017) High thermoelectric performance in (Bi_(0.25)Sb_(0.75)_2 Te_3 due to band convergence and improved by carrier concentration control. Materials Today, 20 (8). pp. 452-459. ISSN 1369-7021. doi:10.1016/j.mattod.2017.02.007.

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Bi_2Te_3 has been recognized as an important cooling material for thermoelectric applications. Yet its thermoelectric performance could still be improved. Here we propose a band engineering strategy by optimizing the converging valence bands of Bi_2Te_3 and Sb_2Te_3 in the (Bi_(1−x)Sb_x)_2Te_3 system when x = 0.75. Band convergence successfully explains the sharp increase in density-of-states effective mass yet relatively constant mobility and optical band gap measurement. This band convergence picture guides the carrier concentration tuning for optimum thermoelectric performance. To synthesize homogeneous textured and optimally doped (Bi0.25Sb0.75)2Te3, excess Te was chosen as the dopant. Uniform control of the optimized thermoelectric composition was achieved by zone-melting which utilizes separate solidus and liquidus compositions to obtain zT = 1.05 (at 300 K) without nanostructuring.

Item Type:Article
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Snyder, G. Jeffrey0000-0003-1414-8682
Additional Information:© 2017 Elsevier Ltd. Available online 28 June 2017. The authors would like to acknowledge funding from the Solid-State Solar-Thermal Energy Conversion Center (S3TEC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0001299. H.-S. Kim gratefully acknowledge financial support from Samsung Advanced Institute of Technology (SAIT). H.-S. Kim would like to thank fruitful discussions with Prof. Yanzhong Pei (Tongji University) and Dr. Heng Wang (University of California, Berkeley). Lastly, H.-S. Kim would also like to acknowledge the time and efforts that Prof. Teruyuki Ikeda (Ibaraki University) has put to build the zone-levelling furnace used in the lab.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0001299
Samsung Advanced Institute of TechnologyUNSPECIFIED
Issue or Number:8
Record Number:CaltechAUTHORS:20170707-114248386
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Official Citation:Hyun-Sik Kim, Nicholas A. Heinz, Zachary M. Gibbs, Yinglu Tang, Stephen D. Kang, G. Jeffrey Snyder, High thermoelectric performance in (Bi0.25Sb0.75)2Te3 due to band convergence and improved by carrier concentration control, In Materials Today, Volume 20, Issue 8, 2017, Pages 452-459, ISSN 1369-7021, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78854
Deposited By: Ruth Sustaita
Deposited On:07 Jul 2017 20:11
Last Modified:15 Nov 2021 17:43

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